The present invention relates to new urea derivatives having pesticidal activity, particularly a fungicidal activity. The urea derivatives according to the invention correspond to the general formula ##STR2## wherein X, Y and Z represent hydrogen or halogen atoms and at least one of the substituents X, Y or Z represent a halogen atom. If there is more than one halogen atom, they may be the same as or different from one another.
The term halogen atom as used herein refers to fluorine, chlorine bromine. Chlorine and fluorine are preferred. Particularly preferred are compounds of Formula I which contain one to two chlorine atoms and possibly a fluorine atom.
The new urea compounds are prepared by methods which are known such as reactng a suitable aniline with methyl isocyanate or by reacting a suitable isocyanate with methylamine. The reactions for obtaining the ureas of the present invention are carried out in an inert solvent at temperatures between the ambient temperature and that of the boiling temperature of the reaction mixture. Suitable solvents include, for example, aromatic hydrocarbons such as toluene or xylene or ethers such as dioxane or tetrahydrofuran.
The starting materials required for the above described reactions may themselves be prepared according to known general methods. A suitably substituted, usually chlorinated, nitrobenzene is reacted with phenol or with a phenol which has first been reacted with potassium hydroxide. This gives a similarly substituted 2-nitro-diphenyl-ether. This product may be further reacted with potassium fluoride in a solvent if it is desired to replace a chlorine on the ring. The chlorinated or fluorochlorinated 2-nitro-diphenylether may be hydrogenated to give the suitably substituted aniline for reaction with methyl isocyanate or it may be reacted with phosgene to obtain the suitably substituted aniline for reaction with methyl isocyanate or it may be reacted with phosgene to obtain the suiltably substituted isocyanate for reaction with methylamine. These two latter reactions provide the substituted ureas of the present invention.
The compounds of Formula (I) are suitable for use as active ingredients in pesticidal compositions. They are fungicidally active, particularly against the fungi of the genus Tilletia and are particularly suitable as active ingredients in fungicical compositions for the protection of cereal grains from smut.
When they are used for this purpose, they are particularly advantageous because of their favorable ecological characteristics, since the urea compounds made in accordance with the present invention are rapidly degraded to harmless products. The same is not true for other wellknown anti-fungal agents such as pentachloronitrobenzene ("quintozene") whose metabolites such as pentachloroaniline and pentachlorothioanisol are persistent pollutants. Moreover, with the active compounds made according to the present invention, there is no danger of contamination by hexachlorobenzene.